package com.min.juc;

import java.util.concurrent.CountDownLatch;

/**
 * CountDownLatch，一个同步辅助类，在完成一组正在其他线程中执行的操作之前，它允许一个或多个线程一直等待。
 * 构造方法参数指定了计数的次数 countDown方法，当前线程调用此方法，则计数减一 。awaint方法，调用此方法会一直阻塞当前线程，直到计时器的值为0
 * @author min
 */
public class TestCountDownLatch {

	public static void main(String[] args) {
		final CountDownLatch latch = new CountDownLatch(10);
		LatchDemo ld = new LatchDemo(latch);
		long start = System.currentTimeMillis();
		for(int i=0;i<10;i++) {
			new Thread(ld).start();
		}

		try {
			latch.await();
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		System.out.println("消耗时间:"+String.valueOf(System.currentTimeMillis()-start));
	}
}


class LatchDemo implements Runnable{
	private CountDownLatch latch;
	public LatchDemo(CountDownLatch latch) {
		this.latch = latch;
	}
	@Override
	public void run() {
		synchronized (this) {
			try {
				for (int i = 0; i < 50000; i++) {
					if (i % 2 == 0) {
						System.out.println(i);
					}
				}
			} finally {
				latch.countDown();
			}
		}
	}
}